1. Field of the Invention
The present invention relates to a sheet adhesive by pressure application, that is, a sheet which, when presented on a surface to which it is desired to be pasted, is effectively pasted only after application of a pressure. Such a structure has the advantage that an accurate positioning can be performed before definitive fixing.
2. Discussion of the Related Art
FIG. 1 shows in perspective and partial cross-sectional view a known sheet adhesive by pressure application, such as described in European patent application EP-A-0429269. This sheet includes a substrate 10 uniformly covered with an adhesive layer 12. Domes 14 are regularly distributed on adhesive layer 12. Domes 14 are formed of microballs 16 deposited on the surface of adhesive layer 12. Thus, domes 14 are not adherent.
Domes 14 are used to avoid that adhesive layer 12 contacts the surface on which the adhesive sheet is laid. The sheet can thus be displaced in contact with the surface to the desired position. A pressure is then applied on the sheet, which results in driving domes 14 into the adhesive layer and bringing the adhesive layer to contact with the surface.
A disadvantage of this adhesive sheet is that adhesive layer 12 must be relatively thick to accomodate domes 14 of sufficient height, which makes it of more difficult fabrication.
Further, any adhesive layer, especially that of the type of FIG. 1, has the disadvantage of trapping air bubbles upon pasting, which is prejudicial to aesthetics in the case where the sheet has a decorative function. This disadvantage is all the more difficult to avoid as the sheet surface area is significant, which makes the use of these adhesive sheets unpractical for wall paper, for example.